### Square Areas

Can you work out the area of the inner square and give an explanation of how you did it?

### Dissect

What is the minimum number of squares a 13 by 13 square can be dissected into?

### 2001 Spatial Oddity

With one cut a piece of card 16 cm by 9 cm can be made into two pieces which can be rearranged to form a square 12 cm by 12 cm. Explain how this can be done.

# Coloured Edges

##### Age 11 to 14 Challenge Level:

 There is a set of tiles which are all different and coloured just on the edges. Each edge on a tile is a different colour. For example: Altogether $10$ different colours are used for the edges, and there is an equal number of edges of each colour used throughout the set. The whole set of tiles is used to make a square. This has a green and blue border. There are no green or blue tiles anywhere in the square except on this border. How many tiles are there in the set?